This invention relates to apparatus for testing electron tubes and more particularly for apparatus for production type detection of interelectrode open and short circuits in a television picture tube.
In production type fabrication of television picture tubes, it is highly desirable to automatically check the electrical characteristics of the components of the tube both before and after the components have been assembled into a finished tube. Among the tests to be made is a determination of the existence of short circuits between electrodes or open circuits between the terminal pins and the electrodes themselves. In a conventional color television picture tube having three cathode electrodes, a G1 electrode and a G2 electrode, there should be no electrical continuity between these electrodes. Consequently, it is essential to test for short circuits between the G1 and G2 electrodes, the three cathode electrodes and the G1 electrode and between the cathode electrodes themselves.
In addition to checking for short circuits, it is also necessary to check for the existence of open circuits which may be present between the terminal pins of the tube and their associated electrodes. It is expedient to be able to test for open circuits by making the measurement connections to the terminal pins only without having to contact the actual electrode itself. This is not only expedient but imperative when the electrodes have been sealed within the tube.